1. Field of the Invention
The present invention generally relates to vessel hulls and more specifically to an improved hybrid hull form for mono-hull planing vessel having hybrid characteristics of both catamarans and conventional V-bottom hull forms.
2. Description of Related Art
V-shaped hull bottoms are well known in the marine industry, including semi-V and deep-V hull bottoms, with respect to both planing vessels and displacement vessels. Planing hulls, whether monohull catamaran or otherwise, are typically used in both off-plane and on-plane conditions. In off-plane conditions, the weight of the vessel is supported by the buoyant force created by the hull geometry. However, a planing hulls is also designed to develop significant lifting forces at higher speeds which allows it to skim across the water's surface with a portion of the forward hull above the surface, known as an “on-plane” condition. When planing hull vessels are “on plane,” hydrodynamic lift, rather than displacement, supports the weight of the vessel. The particular dimensions, deadrise, strake and chine line features of the hulls vary tremendously depending on the type of vessel. These features can significantly affect ride quality, speed and maneuverability of the vessel, amongst other characteristics and functions. Such boats include without limitation recreational craft, cruisers, yachts, and speed boats.
In comparison to mono-hull vessels, conventional catamarans are twin-hulled sailing and powered boats that typically employ two discrete demi-hulls with high length-to-beam ratios which are separated from one another by a central platform, helm, occupant or cockpit area. Catamarans vary tremendously in size, sailing and/or power vessels, and are well known in the art. Catamarans are successful as recreational vessels due to their tremendous stability and speed; however, some maneuvering characteristics are uncomfortable and overall agility is not in line with monohull performance.
Several attempts have been made to combine the features of various known hull designs in order to optimize ride, handling, and running speed characteristics; however, none have successfully improved handling and stability characteristics of mono-hull designs, particularly during maneuvering, nor other benefits as set forth in the present invention.
For example, the U.S. Pat. No. 6,629,507 to Biddison is entitled CHINE SYSTEM FOR A BOAT HULL and discloses a chine design system for a boat wherein the chine member is coupled to the bottom of the hull at a “base edge” and protrudes vertically in a direction away from the boat hull. A curved member couples the extended edge of the first set of chines to the angled panel members of the boat hull. The purpose of this design is to reduce noise levels and low speed by covering otherwise hard chines with curved geometry. The result is reduced noise but not improved running dynamics.
U.S. Pat. No. 6,213,824 to Small is entitled METHOD FOR REDUCING VESSEL DRAFT, and illustrates a boat hull having a design meant to reduce vessel draft, and includes unique tunnels which are open bottomed in one section and extend longitudinally within the hull to form “chutes” for deeper hull sections located in the aft section of the vessel. A super-cavitating propeller is positioned in the aft section of the tunnel. The chute is defined in cross-section as a channel which opens downwardly and can be generally rectangular. The inlet of the chute becomes a lifting surface for the vessel. The invention claims that the vessel has improved shallow water operation without encountering the losses normally associated with shallow draft drive systems or water jets. While the centerline propeller tunnel may reduce draft and drag, the vessel maintains a standard v-shaped monohull and thus may have less than desirable handling characteristics.
U.S. Pat. No. 4,492,176 to Arima is entitled BOAT HULL and illustrates designs for a boat hull having a pair of stern strakes which project rearwardly from the transom of the boat for the intended purpose of improving planing efficiency. The strakes have inner surfaces which ostensibly reduce side slipping of the vessel, and the patent recites varying length-to-width ratios of optimum design. While some performance enhancements may be seen by this design, it is still a traditional v-hull bottom and will lack desired stability in certain conditions.
U.S. Pat. No. 5,191,853 to Adler describes a stepped hydroplane hull wherein the aft section has a positive trim angle and a forward portion has either a flat or positive trim angle wherein the angle of the forward portion is less than that of the aft portion. The hull also includes a region immediately aft of the step which is ventilated to atmosphere by air passages joining the step above the water line, in order to reduce drag at pre-planing speeds when the step is completely immersed in water. The air passages are not longitudinally placed and ventilation actually occurs through the hull. As with traditional stepped hull designs, the keel of the hull is stepped as well, decreasing handling stability at high speeds.
U.S. Pat. No. 7,055,451 to Kalil is entitled VESSEL HULL and describes a vessel having a pair of vents formed in the chine on either side of the rear section allowing air to be introduced to the bottom of the vessel. However, this patent is merely a vented pocket added to a traditional V-shaped hull form and does not include semi-sponson geometry that would otherwise improve static and dynamic ability the hull as described in the present invention.
Other examples of isolated hull features include U.S. Pat. No. 3,996,869 which has limited sponsons that are not incorporated into the entire length of the hull, and U.S. Pat. No. 4,192,248 which discloses limited, very narrow sponsons only in the forward sections of the hull. The sponsons in these inventions are not being used to generate lift so much as to create an aerated tunnel beneath the hull and accordingly very little stability benefits are introduced into the designs.
Japanese Patent No. JP6-227478 to Yamashita describes a hull design having a forward stepped section, a longitudinally oriented keel, a transverse hydrofoil, and catamaran-like side hulls. The hull results in a main center hull stabilized by smaller demihulls with a hydrofoil connecting the demihulls, with the hydrofoil generating planing lift.
There are also a number of flat bottomed models and join boats existing in the market which are typically “stiffer” (reduced roll motions when off plane). They typically have a rectangular hull form when viewed in plane. Although somewhat stable in off-plane conditions, these designs experience very jarring accelerations in adverse conditions when on plane and can only be used comfortably in very calm water. Additionally, these rectangular hulls suffer from difficulty maintaining a steady course due to the lack of directional stability offered by a V-shaped hull.
Consequently, there is a marked need for an improved hull design that enhances the overall performance and ride quality of V-bottomed planing hulls. Such vessels often experience significant rolling motions due to the movement of passenger weight when off plane. There is also a tendency to bank (roll towards the center of turning circle) in high speed turns. These two roll related motions tend to cause discomfort for boat occupants to which present invention is directed at minimizing or eliminating.
It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed. However, in view of the hull designs in existence at the time of the present inventions, it was not obvious to those persons of ordinary skill in the pertinent art as to how the identified needs could be fulfilled in an advantageous manner, nor to design a hybrid hull having the structural and functional features set forth herein.